The vast majority of connections of piping components (pipe, valves, fittings, etc.) require the connection to be permanent and not something that can be disassembled like a threaded or flanged connection (i.e. mechanical joint). Depending on the piping system materials, permanent jointing methods such as solvent cementing, heat fusion, welding and fiberglass hand layup have been utilized. However, each one of these methods presents challenges varying from VOC emissions to the need for power tools and all heavily rely on skilled labor for the success of the union.
More recently adhesive products (bonding agents) have been developed for joining thermoplastic, thermoset, and metallic pipe and fittings for a multitude of applications (both pressure and non-pressure). Though bonding agents have been in use for decades, they typically have not been strong enough to handle the harsh environments of some piping installations. Newer adhesives can and do stand-up to the harshest of pressure and non-pressure piping environments. These new bonding agents can be applied via brush application or via injection. In a brush application, the bonding agent is applied to the pipe end and/or fitting socket with a brush prior to assembly. The brush method may require that special attention be paid to assembly techniques in order to avoid depositing into the piping water-way excess bonding agent or having excess adhesive drip from the socket entrance. The brush method may also require special attention to pipe and fitting tolerances as well as pipe and fitting out of roundness.
Prior injection application methods may involve cumbersome clamps and sealing devices that are installed prior to injecting a bonding agent. These cumbersome clamps and sealing devices incorporate some form of secondary additional seal at the socket bottom to prevent leakage of the bonding agent during the injection process.